{"id":18927,"date":"2023-08-29T07:15:33","date_gmt":"2023-08-29T11:15:33","guid":{"rendered":"https:\/\/ops.group\/blog\/?p=18927"},"modified":"2023-08-29T12:20:45","modified_gmt":"2023-08-29T16:20:45","slug":"cpdlc-gotcha","status":"publish","type":"post","link":"https:\/\/ops.group\/blog\/cpdlc-gotcha\/","title":{"rendered":"CPDLC Gotcha: Clearance Busts"},"content":{"rendered":"<h5>Key Points<\/h5>\n<ul>\n<li>The FAA has published a new\u00a0<a href=\"https:\/\/www.faa.gov\/other_visit\/aviation_industry\/airline_operators\/airline_safety\/safo\/all_safos\/SAFO23005.pdf\" target=\"_blank\" rel=\"noopener\" data-saferedirecturl=\"https:\/\/www.google.com\/url?q=https:\/\/group.us2.list-manage.com\/track\/click?u%3Db75fb5761dc5600b058300642%26id%3D999d31fb21%26e%3D7fa679b52a&amp;source=gmail&amp;ust=1693397704191000&amp;usg=AOvVaw0n5S5aKqx0zU3ogV_-UV2U\">Safety Alert<\/a> for CPDLC and partial route re-clearances.<\/li>\n<li>Make sure you load your full SID manually into the FMS after you receive a partial reroute message (UM79).<\/li>\n<li>Also, don&#8217;t mistake these partial reroute messages as being cleared to fly directly to the waypoint (a direct clearance would be a UM74 message).<\/li>\n<\/ul>\n<h4>Lessons from Teterboro<\/h4>\n<p>In 2022, the FAA recorded <strong>20 aircraft deviations<\/strong> at KTEB\/Teterboro Airport due to <strong>issues with CPDLC and partial reroute messages.<\/strong><\/p>\n<p>These incidents resulted from failure to reload SIDs after receiving a partial reroute UM79 message (where you are cleared to a particular waypoint via other waypoints en-route), requiring swift coordination with ATC to avoid traffic.<\/p>\n<p>But the issue isn\u2019t limited just to Teterboro &#8211; it could happen at any US airport, to any aircraft type receiving a clearance in this way.<\/p>\n<h4>Another thing to watch out for<\/h4>\n<p>Due to limitations in the formatting of CPDLC DCLs, they can be easy to misread or misunderstand. Take the following for example, courtesy of an OPSGROUP member.<\/p>\n<p><strong>A change to a clearance<\/strong> was received by a B777 at <strong>KJFK\/New York<\/strong>\u00a0during taxi and under considerable pressure to get <em>underway or out of the way<\/em>:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-large wp-image-18933\" src=\"https:\/\/ops.group\/blog\/wp-content\/uploads\/2022\/06\/JFKclearance-1024x768.jpg\" alt=\"\" width=\"1024\" height=\"768\" srcset=\"https:\/\/ops.group\/blog\/wp-content\/uploads\/2022\/06\/JFKclearance-1024x768.jpg 1024w, https:\/\/ops.group\/blog\/wp-content\/uploads\/2022\/06\/JFKclearance-300x225.jpg 300w, https:\/\/ops.group\/blog\/wp-content\/uploads\/2022\/06\/JFKclearance-768x576.jpg 768w, https:\/\/ops.group\/blog\/wp-content\/uploads\/2022\/06\/JFKclearance-1536x1152.jpg 1536w, https:\/\/ops.group\/blog\/wp-content\/uploads\/2022\/06\/JFKclearance-2048x1536.jpg 2048w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/>Unfortunately, in this instance the crew <strong>mis-interpreted their clearance as direct to the waypoint YNKEE.<\/strong> This was further compounded by the issue above \u2013 when the new route was loaded, <strong>their SID was dropped from the flight plan.<\/strong><\/p>\n<p>When they got airborne, ATC immediately began asking why they weren\u2019t following the assigned SID \u2013 the result was a <strong>clearance bust.<\/strong> To their surprise, further down the clearance was indeed an assigned SID \u2013 the SKORR4. It was an understandable and easy miss.<\/p>\n<p>The question remained though: <em>what then is the intention of the top part of this clearance if not to clear the aircraft direct to YNKEE?<\/em> We put this to the group, and received some useful feedback.<\/p>\n<p>It maybe comes down to a machine readability issue. The section above the plus signs is required because of the way the clearance is written, and is related to the same issues as above. <strong>It will not contain a SID when you insert it.<\/strong><\/p>\n<p>In fact, some newer CPDLC systems don\u2019t even show that section to the crew \u2013 only the information below the plus signs which contains the assigned SID. The full version is a <strong>confusing<\/strong>, and seemingly <strong>contradictory<\/strong> set up.<\/p>\n<h4>What about PDCs?<\/h4>\n<p>It&#8217;s probably worth a mention that these issues <strong>don&#8217;t affect PDC clearances.<\/strong> PDCs are different and are sent by a service provider via VHF datalink. No log on is needed, and only one can be issued for a flight number at specific airport over a 24 hour period. They also have to be read back via voice. PDC&#8217;s cannot be used to notify pilots of a change to the filed route. So it&#8217;s smooth sailing in that regard.<\/p>\n<h4>Further reading.<\/h4>\n<p>You can read the FAA&#8217;s new <strong>Safety Alert for CPDLC and partial route re-clearances<\/strong> <a href=\"https:\/\/www.faa.gov\/other_visit\/aviation_industry\/airline_operators\/airline_safety\/safo\/all_safos\/SAFO23005.pdf\" target=\"_blank\" rel=\"noopener\">here<\/a>.<\/p>\n<p class=\"p1\">The FAA also has a<a href=\"https:\/\/ops.group\/blog\/wp-content\/uploads\/2022\/07\/DCIT-NAS-Data-Communications-Guide-v12.0_Final.pdf\"> <span class=\"s2\">handy guide<\/span><\/a> on <strong>how to use<\/strong> <b>CPDLC in US airspace.<\/b> It covers the basics, along with departure clearances (DCLs), en route ops, speed\/time restrictions, emergency use and free text.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Key Points The FAA has published a new\u00a0Safety Alert for CPDLC and partial route re-clearances&#8230;.<\/p>\n","protected":false},"author":49,"featured_media":18932,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[1040,48,68],"class_list":{"0":"post-18927","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-briefings","8":"tag-clearance","9":"tag-cpdlc","10":"tag-us"},"_links":{"self":[{"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/posts\/18927","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/users\/49"}],"replies":[{"embeddable":true,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/comments?post=18927"}],"version-history":[{"count":18,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/posts\/18927\/revisions"}],"predecessor-version":[{"id":23242,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/posts\/18927\/revisions\/23242"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/media\/18932"}],"wp:attachment":[{"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/media?parent=18927"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/categories?post=18927"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/tags?post=18927"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}